ANGIOSPERM REPRODUCTION AND BIOTECHNOLOGYBy: Josh Proal, Ben Shapero, and Zach Evans Ch.

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LIFE CYCLELife cycle alternates between haploid and diploidSporophyte – diploid, makes haploid gametes called gametophytes

Gametophyte – haploid, makes diploid gametes called sporophytes

Sporophyte is the dominant generation due to its size and lifespan

FLOWER STRUCTUREStamen – male parts: anther and filament• Anther – terminal spot where pollen grains with

male gametes form• Filament – stalk of a stamenCarpel – female parts: stigma, style, and ovary• Stigma – sticky part of a flower’s carpel which

traps pollen grains• Style – stalk of a flower’s carpel• Ovary – where the egg-containing ovules

developPistil – one or many fused carpelsPetal – modified leaf of a flower designed for attracting insects and other pollinatorsSepal – modified leaf that helps enclose and protect the flower bud before it opens

CHARACTERISTICS OF FLOWERS

Complete Flowers – possess all four floral organsIncomplete Flowers – lacks on or more of the four floral organsSymmetry – radial (roses) or bilateral (tulips) in flowersOvary Location – superior, semi-inferior, and inferior

In superior, stigma is above stamen (III)In semi-inferior, stigma is planar with stamen (II)In inferior, stigma is below stamen (I)

Inflorescence – cluster of incomplete flowers (sunflowers)Monoecious – stamen and carpels are on the same plant (maize)Dioecious – stamate flower and carpellate flowers are on different plants (willows)

DEVELOPMENT OF GAMETOPHYTES

SPORESMicrospore - a spore from a heterosporous plant species that develops into a male gametophyteMegaspore – a spore from a heterosporous plant species that develops into a female gametophyteSelf-incompatibility – the ability of a plant to reject its own pollen and sometimes pollen of closely related individuals RNA hydrolyzing enzymes kill pollen with recognizable self-alleles within

the styleExamples: Dioecious plants can’t self-pollinate

Different flowers mature at different times

DOUBLE FERTILIZATION

Plants have twice as much fun: two sperm per pollen grain. One fertilizes the egg, the other fertilizes the polar nuclei

Zygote = egg + sperm

Endosperm nucleus = 2 polar bodies + sperm

Holds the nutrition for the new plant

ENDOSPERM / EMBRYO DEVELOPMENT

Endosperm development precedes embryonic development: Triploidy nucleus divides, forms a multinucleate “supercell” with a milky

consistency (coconut milk) Eventually, the naked cells form cell walls and become solid endosperm (coconut

“meat”)Embryonic development Egg splits into terminal and basal cells: terminal cell forms proembryo and

cotyledon, basal cell forms suspensor – anchors the embryo to the parent

FRUIT

Cotyledon – a seed leaf of an angiosperm embryo

Monocot – has only cotyledon (maize and other grasses)

Eudicot – has more than one cotyledon (castor bean)

Simple fruit Aggregate fruitMultiple fruit

SEED GERMINATION Dormancy – condition of low metabolic rate and suspension of growth Germination of seeds depends on imbibition – process of water using the

low water potential of the dry seed, causes the coat to rupture and the seed to leave dormancy

REPRODUCTION Asexual Reproduction – offspring derived from a single parent without

genetic recombination

Vegetative Reproduction – type of asexual reproduction in plants, offspring are usually mature fragments from the parent plant. Good if the organism is well-adapted, bad if the environment changes

Fragmentation – when a parent plant separates into parts, creating new plants

Apomixis – Seeds have diploid cells like an embryo, so seeds are clones of the original plant without recombination (ex dandelions)

BIOTECHNOLOGY Cutting – growing a plant from a section of another plant

Grafting – attaching a scion (branch) to a root system (stock) to create a chimera plant with characteristics of both (ex: growing potatoes and tomatoes on the same plant)

Protoplast Fusion – enzymatically removing the cell walls of two plants cells, then fusing those cells to create a new polyploidy species

Artificial Selection – breeding for certain traits

ISSUES WITH BIOTECHNOLOGY

Ethics – can we make new species?

Health – what if they’re bad for us? What if their genes have harmful consequences?

Transgene Escape – weeds hybridize with chimera crop or transgenic seeds escape Modified plants are designed with defunct chloroplast DNA that only works in F1

generation Terminator genes are inserted to kill the plant when exposed to certain factors